JY-MARINE Boat stern bow eye tie down U bolt designed for fastening products to pipe, wood, etc Suitable for automotive, plumbing and other home and industrial applications Plate and nuts included Excellent for marine and other outdoor applications. the threads are M6, not 1/4. Arm centers are 35mm apart. Unthreaded portion between plate position and thread is 20mm, so the substrate needs to be at least that thick. Installed height/width is 43mm. All parts are good quality 316 stainless steel and well made.